1. Field of the Invention
This invention relates to electromagnetic radiation scanning apparatus and methods, and more particularly to radiation director apparatus and method using piezoelectric movement.
2. Description of the Related Art
Most scanning bar code readers use a spinning motor to rotate a multi-faceted mirror; hexagonal mirror facets are typical. Less commonly, other bar code readers use a voice coil to deflect a flat mirror. A laser beam is reflected off the mirror to a scanning area, where it reflects off the bar code carried by an object to be identified and is sensed by an optical detector. The mirror""s rotation causes the laser beam to scan across the area, with the scan repeated as the beam strikes each successive mirror facet.
Scanning stations of this type provide a very convenient mechanism for identifying objects, such as in a retail checkout station or on a production line. However, motors employed are relatively bulky and heavy, and consume significant amounts of power.
In one embodiment of the invention, a radiation director is coupled to move under the control of a piezoelectric element, and a radiation source is configured to direct electromagnetic radiation towards the radiation director. The radiation director directs the radiation under the control of the piezoelectric element.
In another embodiment of the invention, a scanning station comprises a piezoelectric element, an electrical signal source connected to cause the piezoelectric element to vibrate, a radiation director coupled to move under the control of the piezoelectric element, a radiation source configured to direct electromagnetic radiation towards the radiation director, with the director directing the radiation, under the control of the piezoelectric element, toward an object, and a radiation detector positioned to detect radiation from an object scanned by the radiation.
In a radiation scanning method embodiment of the invention, a piezoelectric element is caused to move in a reciprocating fashion, and the movement of the piezoelectric element is used to direct an electromagnetic radiation beam in a scanning motion.
These and other features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.